American Society of Civil Engineers

Stop Logs for Emergency Spillway Gate Dewatering

by Derek R. Freckleton, (Research Assistant, Utah Water Research Laboratory, Logan, UT 84321. E-mail:, Michael C. Johnson, P.E., (corresponding author), M.ASCE, (Research Assistant Professor, Utah State Univ., 8200 Old Main Hill, Logan, UT 84322 E-mail:, M. Leslie Boyd, P.E., M.ASCE, (Hydraulic Engineer, Freese & Nichols, 10814 Jolleyville Rd., Building 4, Suite 100, Austin, TX 78759. E-mail:, and Dustin G. Mortensen, P.E., (Hydraulic Engineer, Freese & Nichols, 10814 Jolleyville Rd., Building 4, Suite 100, Austin, TX 78759. E-mail:

Journal of Hydraulic Engineering, Vol. 137, No. 6, June 2011, pp. 644-650, (doi:

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Document type: Journal Paper
Discussion: by Richard L. Stockstill E-mail: and et al.    (See full record)
Closure:(See full record)
Discussion: by R. G. Patil E-mail:    (See full record)
Abstract: Emergencies resulting in uncontrolled flow through spillway gates often lead to millions of dollars lost to repairs, lack of dam productivity, property damages, and risks to public health and safety. A considerable need exists for reliable emergency dewatering systems to prevent these consequences. Stop logs are the most commonly used dewatering system for spillway gates but are typically designed for maintenance purposes only. They have been found in most cases to be unreliable for emergency closure under flowing conditions. Considering the economic advantages a dewatering system would provide were it functional for the dual purposes of maintenance as well as emergency closure, a new stop log design was developed. This study assesses the design that enables deployment under no-flow conditions as well as flowing, or emergency conditions. The information found in this study provides dam owners, operators, and engineers with options to reduce damages resulting from uncontrolled releases owing to partial or complete failure of spillway gates, including the failure of gates to close after having been raised.

ASCE Subject Headings:

Author Keywords:
Stop logs
Emergency closure
Spillway gate
Dewatering system